Koi disease is usually present in fish at low levels. Their immune system keeps problems under control. However, when they become anxious this lowers levels of protection. This leaves them open to parasites and viruses. The importance of treating this immediately cannot be stressed enough.
Identifying Koi Disease
Sometimes you can tell just by looking if your koi are becoming ill. One sign is the growth of a fungal infection which has a cotton looking growth. Other times it will take testing to ensure the koi are healthy. Mucus samples from koi that are known to be healthy can be taken. When disease is suspected, take mucus samples from the koi you suspect are sick.
When these two samples are compared you should have your answer. If you suspect koi disease it is important to increase oxygen levels in the pond. The problem causing them stress should be removed. The treatment depends upon the levels to which the disease has progressed.
Treating Koi Disease
The treatment of koi disease will usually be a medication. The type of medication could be beneficial as well as harmful. The chemicals used are harmful to the plant life in your pond. It can also harm the koi by slowing the growth of bacteria that is necessary to maintain a healthy balance in your pond.
Viruses are often the cause of problems for koi. Normally koi will use immune systems to cure themselves. However, there is a solution. Similar to the vaccinations that help children to prevent disease, there are some available for koi as well. The treatment in effect causes a form of the disease and forces the immune system of the koi to fight by building antibodies.
This vaccination process is normally a bath or dip which the koi are put into for a certain period of time. However, there are vaccinations which can be given as well. This is one time you will need to know the weight of the koi to prevent overdosing.
One type of virus common to koi is called koi pox. SVC and KHV are also two types of viruses that affect koi. The cure depends upon the koi themselves. Their immune system is responsible for curing the virus.
Parasites are another form of disease known to affect koi. They are called protozoa and are usually quite easy to cure. The use of malachite green and formalin is required. The protozoa will latch on to the skin of the koi and feed off their skin. The other type is metazoa which in some cases are fish lice, tapeworms and leeches. The treatment is usually salt baths and if that does not seem to work malachite green may be used.
If you are going to have a koi pond the best idea is to keep track of what is going on with your koi. Certain disease has been known to wipe out a whole koi pond. Knowing what to do and how to recognize symptoms is the key to a healthy koi pond.
Monday, November 8, 2010
Tuesday, October 19, 2010
Nitrogen Cycle
In a koi pond, ammonia is broken down by naturally occurring bacteria, firstly to nitrite, which is also poisonous to Koi, and ultimately to nitrate. In the quantities we can expect it, nitrate is not directly poisonous to Koi, although it can be a cause of blanket weed. Nitrate can be removed by other means such as a vegetable filter, or a denitrifying filter that employs different bacteria to convert it to gaseous nitrogen and release it to atmosphere. This biological process is referred to as "The Nitrogen Cycle". In reality, the Nitrogen Cycle works throughout the pond, not in the filter alone. All surfaces will support the necessary nitrifying bacteria. A filter, with the provision of large amounts of medium for bacteria to grow upon, ensures that enough biological action takes place to cope with the ammonia produced by the Koi. The 'biomass' (the bacterial colony) will establish itself to the load imposed upon it therefore it is keyed to the stocking level of fish living in the system.
Nitrosomonas bacteria convert ammonia (NH3) to nitrite (NO2)
Nitrobacter bacteria convert nitrite (NO2) to nitrate (NO3)
When you first introduce fish to a new pond, the main problem is not the solid waste produced by the fish, it is the ammonia(NH3) released into the water. This is very toxic to the fish, especially in a small pond. The first of our friendly bacteria to spring into action are the Nitrosomonas bacteria. These bacteria derive all the energy they need for growth and reproduction from converting ammonia into nitrites. They live in several places such as soil, sewage, fresh water, etc. and they thrive in places where there are high levels of nitrogen compounds. These bacteria need large amounts of energy to divide and multiply and, because of this, it takes a while for them to develop in the pond in such numbers as to be of use. It is, therefore, very important that you do not stock a new pond to capacity immediately when it is initiated.
Once your first fish are put into the system and begin to feed, they will produce toxic ammonia and carbon dioxide (CO2) from their gills and solid waste matter. Ammonia is also introduced into the aquarium by decaying matter such as solid fish waste, uneaten food and dead plant matter. Nitrosomonas bacteria present in the water will begin to convert the ammonia into nitrites (NO2) and, in doing this, will begin to multiply. As the numbers of Nitrosomonas increase and the ammonia levels correspondingly decrease, nitrite levels in the water will rapidly start to increase.
Nitrite is almost as dangerous to fish as ammonia and this is where the second batch of 'friendly' bacteria come into action - the Nitrobacter. These microscopic rod-shaped bacteria begin to colonise the filter and feed on the nitrites (NO2) produced by the Nitrosomonas bacteria. They convert them to nitrates (NO3) which are far less harmful to fish and other animals. In doing this they, too, begin to multiply their numbers until a balance is achieved.
The byproducts, then, of this cycle are the carbon dioxide exhaled by the fish and the nitrates produced by the bacteria. Both of these are used up to some degree by any aquatic plants present. The carbon dioxide is used up by the plants in the action of photosynthesis which produces oxygen back into the water and the nitrates are consumed by the plants as fertilizer to aid their growth.
That is why proper proportions of fish and plants are essential to your pond environment. To give you an idea, a general rule of thumb is that you should have one inch of fish for every square foot of surface area in your pond. 40 – 60 percent of your pond surface should be covered with a mix of marginals as well as floaters. These will not only provide nutrients but will allow your fish some cover from possible predators.
Biofilter
Biofiltration is a pollution control technique using living material to capture and biologically degrade process pollutants. Common uses include processing waste water, capturing harmful chemicals or silt from surface runoff, and microbiotic oxidation of contaminants in air.
Water Treatment
Trickling filters have been used to filter water for various end uses for almost two centuries. Biological treatment has been used in Europe to filter surface water for drinking purposes since the early 1900s and is now receiving more interest worldwide. Biological treatment methods are also common in wastewater treatment, aquaculture and greywater recycling as a way to minimize water replacement while increasing water quality.
For drinking water, biological water treatment involves the use of naturally occurring micro-organisms in the surface water to improve water quality. Under optimum conditions, including relatively low turbidity and high oxygen content, the organisms break down material in the water and thus improve water quality. Slow sand filters or carbon filters are used to provide a place on which these micro-organisms grow. These biological treatment systems effectively reduce water-borne diseases, dissolved organic carbon, turbidity and colour in surface water, improving overall water quality.
Use in aquaculture
The use of biofilters are commonly used on closed aquaculture systems, such as recirculating aquaculture systems (RAS). Many designs are used, with different benefits and drawbacks, however the function is the same: reducing water exchanges by converting ammonia to nitrate. Ammonia (NH4+ and NH3) originates from the brachial excretion from the gills of aquatic animals and from the decomposition of organic matter. As ammonia-N is highly toxic, this is converted to a less toxic form of nitrite (by Nitrosomonas sp.) and then to an even less toxic form of nitrate (by Nitrobacter sp.). This "nitrification" process requires oxygen (aerobic conditions), without which the biofilter can crash. Furthermore, as this nitrification cycle produces H+, the pH can decrease which necessitates the use of buffers such as lime.
Water Treatment
Trickling filters have been used to filter water for various end uses for almost two centuries. Biological treatment has been used in Europe to filter surface water for drinking purposes since the early 1900s and is now receiving more interest worldwide. Biological treatment methods are also common in wastewater treatment, aquaculture and greywater recycling as a way to minimize water replacement while increasing water quality.
For drinking water, biological water treatment involves the use of naturally occurring micro-organisms in the surface water to improve water quality. Under optimum conditions, including relatively low turbidity and high oxygen content, the organisms break down material in the water and thus improve water quality. Slow sand filters or carbon filters are used to provide a place on which these micro-organisms grow. These biological treatment systems effectively reduce water-borne diseases, dissolved organic carbon, turbidity and colour in surface water, improving overall water quality.
Use in aquaculture
The use of biofilters are commonly used on closed aquaculture systems, such as recirculating aquaculture systems (RAS). Many designs are used, with different benefits and drawbacks, however the function is the same: reducing water exchanges by converting ammonia to nitrate. Ammonia (NH4+ and NH3) originates from the brachial excretion from the gills of aquatic animals and from the decomposition of organic matter. As ammonia-N is highly toxic, this is converted to a less toxic form of nitrite (by Nitrosomonas sp.) and then to an even less toxic form of nitrate (by Nitrobacter sp.). This "nitrification" process requires oxygen (aerobic conditions), without which the biofilter can crash. Furthermore, as this nitrification cycle produces H+, the pH can decrease which necessitates the use of buffers such as lime.
Monday, October 11, 2010
Differences from goldfish
Goldfish were developed in China more than a thousand years ago by selectively breeding Prussian carp for color mutations. By the Song Dynasty (960 – 1279), yellow, orange, white and red-and-white colorations had been developed. Goldfish (Carassius auratus) and Prussian carp (Carassius gibelio) are now considered different species. Goldfish were introduced to Japan in the 16th century and to Europe in the 17th century. Koi on the other hand, were developed from common carp in Japan in the 1820s. Koi are domesticated common carp (Cyprinus carpio) that are culled for color, they are not a different species and will revert to the original coloration within a few generations if allowed to breed freely.
In general, goldfish tend to be smaller than koi, and have a greater variety of body shapes, and fin and tail configurations. Koi varieties tend to have a common body shape, but have a greater variety of coloration and color patterns. They also have prominent barbels on the lip. Some goldfish varieties, such as the common goldfish, comet goldfish and shubunkin have body shapes and coloration that are similar to koi, and can be difficult to tell apart from koi when immature. Since goldfish and koi were developed from different species of carp, even though they can interbreed, their offspring are sterile.
In general, goldfish tend to be smaller than koi, and have a greater variety of body shapes, and fin and tail configurations. Koi varieties tend to have a common body shape, but have a greater variety of coloration and color patterns. They also have prominent barbels on the lip. Some goldfish varieties, such as the common goldfish, comet goldfish and shubunkin have body shapes and coloration that are similar to koi, and can be difficult to tell apart from koi when immature. Since goldfish and koi were developed from different species of carp, even though they can interbreed, their offspring are sterile.
Wednesday, October 6, 2010
Choosing Healthy Koi Fish
So you’ve decided to start raising Japanese koi fish? It’s a great adventure, as koi fish (according to us koi enthusiasts anyway!) are among the most satisfying fish to raise, in that they’re beautiful, and even have personalities, as you’ll see when you’re eventually able to hand feed them.
And koi can live for over 20 years, which means that you can experience their development over a long span of time.
The first step to your koi regime though, is to choose healthy and happy koi.
Choosing wisely when you’re buying koi will help ensure that you won’t be disappointed, and that you’ll end up with an investment that will be worth both the money, and the time and effort.
By the time you finish this article, you’ll know the vital tips on how to properly choose koi for your pond.
1. The first decision to make is to whether you want to buy from your local supplier or through the internet. If you have a local koi supplier, go and have a look at the quality of their koi as well as their facilities. Get an idea of how knowledgeable the owner is about koi in general, but more importantly, about the specific koi that he has in stock.
For example, does he know exactly where they have come from, why he chooses those sources, and how long he’s been using those sources? And does he know the lineage of the fish that he has in stock, about their color characteristics, and the health of this years stock compares to the last?
If there are no local suppliers that meet your satisfaction, then you may have to use an internet supplier or auction.
2. The time of the year to buy your koi. If you want imported Japanese koi, which are the best quality koi usually, then the harvest time in Japan in October and so will arrive in overseas countries in November or December.
A large supplier though, or a supplier who receives stock from the US, or other producers such as Singapore, will have stock at all times of the year, so you can purchase them in any season. If you don’t have a heated pond and you have very cold winters where your pond freezes over, November or December may not be the best time to buy.
3. How long has the koi been quarantined before or after they arrive in the country? Usually one month of quarantine is the minimum, though some illnesses may take longer to develop especially in colder temperatures.
Even if they’ve been quarantined and no diseases are evident, if you have existing koi in your pond, it’s best to isolate the new koi in a separate pond for a month at least before introducing them to prevent diseases from being transmitted to your entire collection.
4. How healthy are the koi? It’s important to look for signs of healthy koi fish.
These are
a) that they’re swimming smoothly and efficiently, and not with any jerking or unsmooth motions
b) that the koi is not damaged in any way, looking carefully at their gills, all their scales, their fins, and quality of their eyes. Ensure that there are no damage, ulcerations, or discoloured spots
c) that they’re not in respiratory distress and that their gills are moving evenly and rhythmically
d) that they’re interacting and socialising well. Koi that swim alone or are hiding in a corner may not be the healthiest or most robust.
If you need a closer look at a koi that you like, ask the owner to hold them up close for you to see.
5. How many koi to buy. A common mistake is to buy too many koi for the size of pond, or to put it the other way around, to have too small a pond to begin with. Especially with the Japanese koi, that have the largest growth potential, they can grow to over 2 feet (60 – 70cm) in length, and thus a sufficient volume of water and filtering system is required to keep the water clean and oxygenated.
Generally, you should have 1000L of water for each koi, especially with the Japanese variety. Plus, your pond should be ready before you go buy the koi.
If this is your first ever koi pond, and you’re looking at top of the range koi, it may be wise to not buy your entire stock of expensive koi at once.
It may be wiser to buy a few to test everything out, to make sure that the pond set up that you’ve got is producing good results.
If going for a $10 to $20 koi, then many will be able to afford the whole new family at once.
So there you have it, your first piece of the puzzle when it comes to keeping koi.
You’ve gotten some tips on choosing koi for your pond to help you to maximise your results with this enticing and very rewarding hobby.
Keep learning, especially about koi care and koi pond set ups as well.
Here’s good feng shui to you and your new koi family.
And koi can live for over 20 years, which means that you can experience their development over a long span of time.
The first step to your koi regime though, is to choose healthy and happy koi.
Choosing wisely when you’re buying koi will help ensure that you won’t be disappointed, and that you’ll end up with an investment that will be worth both the money, and the time and effort.
By the time you finish this article, you’ll know the vital tips on how to properly choose koi for your pond.
1. The first decision to make is to whether you want to buy from your local supplier or through the internet. If you have a local koi supplier, go and have a look at the quality of their koi as well as their facilities. Get an idea of how knowledgeable the owner is about koi in general, but more importantly, about the specific koi that he has in stock.
For example, does he know exactly where they have come from, why he chooses those sources, and how long he’s been using those sources? And does he know the lineage of the fish that he has in stock, about their color characteristics, and the health of this years stock compares to the last?
If there are no local suppliers that meet your satisfaction, then you may have to use an internet supplier or auction.
2. The time of the year to buy your koi. If you want imported Japanese koi, which are the best quality koi usually, then the harvest time in Japan in October and so will arrive in overseas countries in November or December.
A large supplier though, or a supplier who receives stock from the US, or other producers such as Singapore, will have stock at all times of the year, so you can purchase them in any season. If you don’t have a heated pond and you have very cold winters where your pond freezes over, November or December may not be the best time to buy.
3. How long has the koi been quarantined before or after they arrive in the country? Usually one month of quarantine is the minimum, though some illnesses may take longer to develop especially in colder temperatures.
Even if they’ve been quarantined and no diseases are evident, if you have existing koi in your pond, it’s best to isolate the new koi in a separate pond for a month at least before introducing them to prevent diseases from being transmitted to your entire collection.
4. How healthy are the koi? It’s important to look for signs of healthy koi fish.
These are
a) that they’re swimming smoothly and efficiently, and not with any jerking or unsmooth motions
b) that the koi is not damaged in any way, looking carefully at their gills, all their scales, their fins, and quality of their eyes. Ensure that there are no damage, ulcerations, or discoloured spots
c) that they’re not in respiratory distress and that their gills are moving evenly and rhythmically
d) that they’re interacting and socialising well. Koi that swim alone or are hiding in a corner may not be the healthiest or most robust.
If you need a closer look at a koi that you like, ask the owner to hold them up close for you to see.
5. How many koi to buy. A common mistake is to buy too many koi for the size of pond, or to put it the other way around, to have too small a pond to begin with. Especially with the Japanese koi, that have the largest growth potential, they can grow to over 2 feet (60 – 70cm) in length, and thus a sufficient volume of water and filtering system is required to keep the water clean and oxygenated.
Generally, you should have 1000L of water for each koi, especially with the Japanese variety. Plus, your pond should be ready before you go buy the koi.
If this is your first ever koi pond, and you’re looking at top of the range koi, it may be wise to not buy your entire stock of expensive koi at once.
It may be wiser to buy a few to test everything out, to make sure that the pond set up that you’ve got is producing good results.
If going for a $10 to $20 koi, then many will be able to afford the whole new family at once.
So there you have it, your first piece of the puzzle when it comes to keeping koi.
You’ve gotten some tips on choosing koi for your pond to help you to maximise your results with this enticing and very rewarding hobby.
Keep learning, especially about koi care and koi pond set ups as well.
Here’s good feng shui to you and your new koi family.
Sunday, October 3, 2010
How Often Do You Feed Koi Fry?
When your koi fry hatch from the eggs, they will immediately attach themselves to any surface and continue to feed on their yolk sac until it is consumed. Then, the fry will rise to the surface to gulp some air and get their swim bladders working. After that, the fry will swim around in search for food.
Some experts do not advise giving your koi fry dry or artificial food for at least 6 to 8 weeks as it (artificial food) can damage the newly developed gills and will likely pollute the pond water. What they also want to avoid is the buildup of ammonia or nitrite that can quickly kill the fry. So how often do you feed koi fry? Experts recommend providing the fry with an ample supply of live, natural food like daphnia and infusoria to ensure their survival and fast growth. To produce daphnia and infusoria, you need to prepare your growing on pond a month before spawning by seeding it with chicken manure or use leaf mould if you are afraid that the manure might contain salmonella.
Still, there are keepers who feed the koi fry with boiled egg yolk during the first few days in order to increase the size of the stomach. You can also give koi fry newly hatched brine shrimp after a week. Then, you may start them on a mash diet – the fine powder ground from high protein koi food. Do give your fry some spirulina and pure wheat germ too. Feed the fry small amounts but often, about four to five times a day during the first three months. As the fry start to grow, you can feed them less often, about three times a day until you can introduce them to a regular diet of koi food, beginning with smaller pellets and gradually increasing the size of pellets until they can also eat what the adults eat.
Some experts do not advise giving your koi fry dry or artificial food for at least 6 to 8 weeks as it (artificial food) can damage the newly developed gills and will likely pollute the pond water. What they also want to avoid is the buildup of ammonia or nitrite that can quickly kill the fry. So how often do you feed koi fry? Experts recommend providing the fry with an ample supply of live, natural food like daphnia and infusoria to ensure their survival and fast growth. To produce daphnia and infusoria, you need to prepare your growing on pond a month before spawning by seeding it with chicken manure or use leaf mould if you are afraid that the manure might contain salmonella.
Still, there are keepers who feed the koi fry with boiled egg yolk during the first few days in order to increase the size of the stomach. You can also give koi fry newly hatched brine shrimp after a week. Then, you may start them on a mash diet – the fine powder ground from high protein koi food. Do give your fry some spirulina and pure wheat germ too. Feed the fry small amounts but often, about four to five times a day during the first three months. As the fry start to grow, you can feed them less often, about three times a day until you can introduce them to a regular diet of koi food, beginning with smaller pellets and gradually increasing the size of pellets until they can also eat what the adults eat.
Thursday, September 30, 2010
Varieties of Koi
Koi varieties are distinguished by coloration, patterning, and scalation. Some of the major colors are white, black, red, yellow, blue, and cream. While the possible color variations are virtually limitless, breeders have identified and named a number of specific categories. The most popular category is Gosanke, which is made up of the Kohaku, Taisho Sanshoku, and Showa Sanshoku varieties.
New koi varieties are still being actively developed. Ghost koi were developed in the 1980s, and have become very popular in the United Kingdom. There are a hybrid of wild carp and Ogon koi, and are distinguished by their metallic scales. Butterfly koi (also known as Longfin koi, or Dragon Carp) were also developed in the 1980s, and are notable for their long and flowing fins. They are hybrids of koi with Asian carp. Butterfly koi and Ghost koi are considered by some to be not true Nishikigoi.
For complete varieties, klik koi varieties page.
Etymology of Koi
The word 'koi' comes from Japanese, simply meaning "carp." It includes both the dull grey fish and the brightly colored varieties. What are known as 'koi' in English are referred to more specifically as 'nishikigoi' in Japan (literally meaning 'brocaded carp'). In Japanese, 'koi' is a homophone for another word that means 'affection' or 'love'; koi are therefore symbols of love and friendship in Japan. An example of this is given in a short story by Mukoda Kuniko, "Koi-san". Koi tattoos have also become a popular trend in North America.
Koi's history
Koi or more specifically nishikigoi, are ornamental domesticated varieties of the common carp (Cyprinus carpio) that are kept for decorative purposes in outdoor koi ponds or water gardens. They are also called Japanese carp. Koi are among the longest-living vertebrates, with some animals living over 200 years. The most popular category of koi is the Gosanke, which is made up of the Kohaku, Taisho Sanshoku, and Showa Sanshoku varieties.
The carp is a large group of fish originally found in Central Europe and Asia. Various carp species were originally domesticated in East Asia, where they were used as food fish. The ability of carp to survive and adapt to many climates and water conditions allowed the domesticated species to be propagated to many new locations including Japan. Natural color mutations of these carp would have occurred across all populations. Carp were first bred for color mutations in China more than a thousand years ago, where selective breeding of the Prussian carp (Carassius gibelio) led to the development of the goldfish
Carp are known as koi in Japan. Of the various domesticated carp species, the common carp (Cyprinus carpio) is one of the more commonly used in aquaculture. The common carp was aquacultured as a food fish as at least as far back as the 5th century in China. The common carp was also known to have been aquacultured in Europe by the Roman Empire, which could have spanned a time period of 27 BC to 400 AD. Common carp were first introduced into Japan by way of China between 400 to 600 years ago. Common carp were first bred for color in Japan in the 1820s, initially in the town of Ojiya in the Niigata prefecture on the north eastern coast of Honshu island. By the 20th century, a number of color patterns had been established, most notably the red-and-white Kohaku. The outside world was not aware of the development of color variations in koi until 1914, when the Niigata koi were exhibited in the annual exposition in Tokyo. At that point, interest in koi exploded throughout Japan. The hobby of keeping koi eventually spread worldwide. Koi are now commonly sold in most pet stores, with higher-quality fish available from specialist dealers.
Extensive hybridization between different populations has muddled the historical zoogeography of the common carp. However, scientific consensus is that there are at least two subspecies of the common carp, one from Western Eurasia (Cyprinus carpio carpio) and another from East Asia (Cyprinus carpio haematopterus). One recent study on the mitochondrial DNA of various common carp indicate that koi are of the East Asian subspecies. However another recent study on the mitochondrial DNA of koi have found that koi are descended from multiple lineages of common carp from both Western Eurasian and East Asian varieties. This could be the result of koi being bred from a mix of East Asian and Western Eurasian carp varieties, or koi being bred exclusively from East Asian varieties and being subsequently hybridized with Western Eurasian varieties (the butterfly koi is one known product of such a cross). Which is true has not been resolved.
The carp is a large group of fish originally found in Central Europe and Asia. Various carp species were originally domesticated in East Asia, where they were used as food fish. The ability of carp to survive and adapt to many climates and water conditions allowed the domesticated species to be propagated to many new locations including Japan. Natural color mutations of these carp would have occurred across all populations. Carp were first bred for color mutations in China more than a thousand years ago, where selective breeding of the Prussian carp (Carassius gibelio) led to the development of the goldfish
Carp are known as koi in Japan. Of the various domesticated carp species, the common carp (Cyprinus carpio) is one of the more commonly used in aquaculture. The common carp was aquacultured as a food fish as at least as far back as the 5th century in China. The common carp was also known to have been aquacultured in Europe by the Roman Empire, which could have spanned a time period of 27 BC to 400 AD. Common carp were first introduced into Japan by way of China between 400 to 600 years ago. Common carp were first bred for color in Japan in the 1820s, initially in the town of Ojiya in the Niigata prefecture on the north eastern coast of Honshu island. By the 20th century, a number of color patterns had been established, most notably the red-and-white Kohaku. The outside world was not aware of the development of color variations in koi until 1914, when the Niigata koi were exhibited in the annual exposition in Tokyo. At that point, interest in koi exploded throughout Japan. The hobby of keeping koi eventually spread worldwide. Koi are now commonly sold in most pet stores, with higher-quality fish available from specialist dealers.
Extensive hybridization between different populations has muddled the historical zoogeography of the common carp. However, scientific consensus is that there are at least two subspecies of the common carp, one from Western Eurasia (Cyprinus carpio carpio) and another from East Asia (Cyprinus carpio haematopterus). One recent study on the mitochondrial DNA of various common carp indicate that koi are of the East Asian subspecies. However another recent study on the mitochondrial DNA of koi have found that koi are descended from multiple lineages of common carp from both Western Eurasian and East Asian varieties. This could be the result of koi being bred from a mix of East Asian and Western Eurasian carp varieties, or koi being bred exclusively from East Asian varieties and being subsequently hybridized with Western Eurasian varieties (the butterfly koi is one known product of such a cross). Which is true has not been resolved.
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